Recently visited the wonderful National Library of Wales, a stately Grade II listed building high on the hillside overlooking the vista of Cardigan Bay at Aberystwyth. I was there to consult the diaries of Tom Jones (not the singer, but the other one), who was Deputy Cabinet Secretary from 1916 to 1930. The building celebrated its centenary a couple of years ago. What I hadn’t appreciated was the role it served during the second world war, acting as a repository for many rare manuscripts (such as the Magna Carta), books, paintings and other artefacts brought from various institutions for safe-keeping. For this purpose, the architect designed a tunnel in an outcrop of rock close to the building. It was specially heated and ventilated and a British Museum expert actually stayed in the library at night to ensure the air conditioning didn’t let them down.